A weight on a spring. Pull it back, release, and watch it race to the middle, shoot past, and rock to and fro — slowly, so you feel the rhythm.
Reach the mark
The green mark sits at the far edge — where the swing turns around. Pull just enough so the weight reaches it and turns. Too soft falls short; too hard shoots past.
Three worlds
Spring — a stiffer spring beats faster. Weight — a heavier weight swings slower. Drag — thick air shrinks each swing until it stops.
Watch teaches
Watch isn't free play — it runs set demos and names the physics as it happens, even two springs side by side to prove the beat. Game is your try. Practice lets you move the mark.
Learn when you ask
It rocks to a rest and sits a moment. When you want the why — Hooke's pull-back, the steady beat — tap 🔬. The science comes only when you ask.
🟢 Real physics · Springs
What just happened
Just now
Why
The rule
Try it
A Lab of Motion
The Spring.
Watch — set demos that show it and name the physics.
Demo 1 of 3
Pull back16
How far you stretch it before letting go. Bigger pull = farther reach.
Stiffness30
🎯 The markdrag on the table
Tap the far side to move where the swing must reach.